Air, Not Oxygen
The first thing know about a scuba diving tank, or tank, is that nigh on always the recreational diver will have it filled with clean air, not oxygen. This is opposite to what lots of television programs would have us believe! It is not an oxygen cylinder - it is an air cylinder.
If it was filled with pure oxygen, diving deeper than about 6m and breathing pure oxygen can actually kill the diver!
What Is In It Then?
Believe it or not, only plain, pure, clean compressed air. Nothing fancy! Your dive centre will use a compressor to suck in air, filter it to eliminate dust particles and water and squash it into the tank so that there is lots to breath on your dive!
Is It Always Merely Fresh Air?
A tank does not always only contain fresh air. Specialist divers utilize nitrox or trimix to permit them to diver deeper and for more time and occasionally, pure oxygen at some point in decompression stops - but just shallower than 6 metres!
What Is A Scuba Diving cylinder Made Of?
The solid, and regularly heavy, tanks are made of aluminum or steel. Pick one up and you will know by the mass which it is - the steel ones are far heavier. For this reason, divers in dry suits, who require more mass to correct the positive buoyancy effects of the exposure suit, may tend to wear the heavier steel tanks to prevent carrying so many loose weights.
How Long Does The Air In A cylinder Last?
This is actually a exceptionally complicated question. In short, the deeper you go, the smaller the tank, the harder you breath, the harder you are swimming etc the shorter the time you will get out of a cylinder.
The problem is that it takes additional air molecules to fill your lungs at depth then on the surface because of the effects of pressure at depth. So at 20 or 30 metres, you are taking plenty more out of the tank with each breath - in fact 3 and 4 times as much respectively.
Swimming hard makes you breath harder and, of course, a 12 litre tank carries loads less air than a 15 litre tank. But, a novice diver should be able to make a 40 to 50 minute dive as long as they aren't going excessively deep!
Why Does The tank Feel Lighter After A Dive
Believe it or not, the variance in weight is the weight of the air that you have breathed! That mass difference is how much air you have gone through during the dive.
What Safety Safeguards Should Be Followed?
Obviously, take care when lifting a dive cylinder - it is heavy! But it is also full of compressed air, so make sure that it is not going to fall over. Take care not to damage the top part where you plug in your regulators, nor loose the o-ring. Also, a tank should never be fully drained. The pressure inside stops moist air from getting in, which can cause rust and damage the inside of the tank.
Author Resource:-
Keith Lunt owns Go Diving. If you want to read more hints and tips, call into the Diving Blog.
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